Fischer-Tropsch Synthesis Performance On Zirconia Supported Co-based Catalyst

Petroleum has always dominated the global energy consumption ratio,however,the imports of crude oil and oil products have increased year by year in our country.Therefore,Fischer-Tropsch synthesis which produces liquid fuels is one of the effective ways to solve the current difficulties.The key to the Fischer-Tropsch synthesis is the development of highly active and highly selective catalysts,and the active metals commonly used are cobalt-based or iron-based catalysts.In this report,cobalt was used as the catalyst active phase to study the influence of supports,catalyst preparation conditions or methods on the Fischer-Tropsch synthesis performance.20 wt%Co-based catalysts supported on ZnO,Al₂O₃ and ZrO₂were prepared by co-precipitation method.The results revealed that Co catalyst supported on ZrO₂ exhibited better FTS catalytic performance than that supported on ZnO or Al₂O₃,and a series of characterizations of the catalysts showed that Co/ZrO₂contains the most surface metal Co.In addition,the selectivity of C₅⁺hydrocarbons had a positive relationship with the adsorption capacity of surface metal Co to H₂.The effect of precipitants?NH₄OH,Na₂CO₃ and NaOH?,pH values?9,11 and 13?and precipitation temperatures?60oC,80oC and 100oC?on the Fischer-Tropsch synthesis performance were also investigated.It was found that when the precipitant was NaOH,the pH value was 13,and the precipitation temperature was 80oC,the prepared Co/ZrO₂ catalyst had the best catalytic performance because of the most surface metal Co.Under suitable preparation conditions,the effect of catalyst preparation methods,suchasco-precipitation,citricacidsol-gelandhydrothermal synthesis-incipient impregnation on the performance of Fischer-Tropsch synthesis was investigated.The results showed that the catalyst prepared by synthesis-incipient impregnation had better catalytic performance and the preparation process is environmentally friendly.After further optimizing the preparation conditions of this method,it was found that the distribution of Co active sites on the catalyst surface and the size of Co particles could be changed by changing the preparation process of hydrothermal synthesis-incipient impregnation method.Thereby,the adsorption and dissociation of H₂ and CO would be affected,and ultimately the Fischer-Tropsch synthesis performance was affected.And when the hydrothermal temperature was 160oC,the precursor was zirconyl nitrate,and the support crystal was monoclinic ZrO₂,the best catalyst performance was obtained.